Spontaneity

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Spontaneity
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Spontaneity
A reaction is spontaneous if it sill occur with
no outside intervention.
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Spontaneity
4Fe 3O2 ? 2Fe2O3 ?H -1625 kJ
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Spontaneity
CH4 2O2 ? CO2 2H2O ?H -891 kJ
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Spontaneity
CH4 2O2 ? CO2 2H2O ?H -891 kJ Some
spontaneous reactions need a little bit of
activation energy.
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Spontaneity
Are all spontaneous reactions exothermic?
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Spontaneity
entropy
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Spontaneity
chaos
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Spontaneity
disorder
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Spontaneity
randonmess
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Entropy
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Entropy always
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Entropy always wins.
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Spontaneity
A reaction is spontaneous if entropy increases.
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Spontaneity
A reaction is spontaneous if entropy
increases. ?Ssystem ?Sproducts - ?Sreactants
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Spontaneity

• Entropy usually increases when
• Liquids vaporize
• Solids melt
• Dissolved gasses bubble out
• The number of gaseous particles increases
• Solids or liquids dissolve
• Temperature increases.

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Spontaneity
Predict the sign of ?S ClF(g) F2(g) ? ClF3(g)
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Spontaneity
Predict the sign of ?S NH3(g) ? NH3(aq)
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Spontaneity
Predict the sign of ?S CH3OH(l) ? CH3OH(aq)
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Spontaneity
Predict the sign of ?S C10H8(l) ? C10H8(s)
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Spontaneity
The biologists question
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Spontaneity
The biologists question If entropy always
increases, how do life forms grow, develop, and
evolve?
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Spontaneity
?Suniverse ?Ssystem ?Ssurroundings